Cyclopentadithiophene and Diketo-pyrrolo-pyrrole fused rigid copolymer for high optical contrast electrochromic polymer.

Two donor-acceptor electrochromic copolymers containing fused rigid units of cyclopentadithiophene and diketopyrrolopyrrole, namely PCPDTT-DPP with benzene and thiophene ring linkers, were successfully synthesized. The electrochromic properties of the copolymers were characterized by cyclic voltammetry, UV-Vis spectroscopy and spectroelectrochemical method. The results demonstrated that the effect of DPP on the copolymer showed the p-type doping with an electrochemical band gap of 1.45 eV. The copolymer showed a higher color contrast changing from purple to transparent with %ΔT of 55% at ±1.0 V vs. Ag/AgCl compared to the parent polymer containing only cyclopentadithiophene unit. The results indicated that the new copolymer could be a potential candidate for electrochromic materials in smart films and windows. [ABSTRACT FROM AUTHOR]